if a wireless interface shows in the output, the kernel sees your NIC and can connect a driver to it, does a wireless interface appear?
Do you have a wired connection so you can post from the booted gentoo system?_________________Defund the FCC.

* Bringing up interface wlp2s0
* Starting wpa_supplicant on wlp2s0 ...
Successfully initialized wpa_supplicant
Line 995: unknown EAP method 'SIM'
You may need to add support for this EAP method during wpa_supplicant
build time configuration.
See README for more information.
Line 995: failed to parse eap 'SIM'.
Line 998: failed to parse network block.
Line 1041: unknown EAP method 'IKEV2'
You may need to add support for this EAP method during wpa_supplicant
build time configuration.
See README for more information.
Line 1041: failed to parse eap 'IKEV2'.
Line 1044: failed to parse network block.
Line 1050: unknown EAP method 'FAST'
You may need to add support for this EAP method during wpa_supplicant
build time configuration.
See README for more information.
Line 1050: failed to parse eap 'FAST'.
Line 1056: failed to parse network block.
Line 1061: unknown EAP method 'FAST'
You may need to add support for this EAP method during wpa_supplicant
build time configuration.
See README for more information.
Line 1061: failed to parse eap 'FAST'.
Line 1067: failed to parse network block.
Failed to read or parse configuration '/etc/wpa_supplicant/wpa_supplicant.conf'.
* start-stop-daemon: failed to start `/usr/sbin/wpa_supplicant' [ !! ]
* ERROR: net.wlp2s0 failed to start

Edit the kernel menuconfig: (do these in the order listed, "<M> BCMA support" must be selected for the "<M> Broadcom IEEE802.11n PCIe SoftMAC WLAN driver" choice to appear ;; "<M> Broadcom IEEE802.11n PCIe SoftMAC WLAN driver" is the only selection you should make under " [*] Wireless LAN --->" unless you have other wifi NIC's::